Redeem the bonus at the casino cashier.
Use the code 15WINNINGSPIN and get $15 free bonus.
Use the code 75YOURTIME and get $75 free bonus.
Use the code 100MASSIVECHIP and get $100 free bonus.
Use the code 65TOPJACKPOT4YOU and get $65 free bonus.
Get lucky!
Even though $100 being the ceiling offer, I still say they should let up eventually combine and add up everything they just offered separately as one bonus